Fix section name in Contribution Analytics

Previously the Contribution Analytics section for pushes was titled
"Push" (singular) even though all other sections were plural. This
fixes that problem by changing the title to "Pushes" (plural).

ee/app/views/groups/contribution_analytics/show.html.haml

@@ -25,7 +25,7 @@
       = s_('ContributionAnalytics|Contribution analytics for issues, merge requests and push events since %{start_date}') % { start_date: @start_date }
 
   %div{ data: { qa_selector: 'push_content' } }
-    %h3= _('Push')
+    %h3= _('Pushes')
     - code_push_count = @data_collector.total_push_count
     - commits_count = @data_collector.total_commit_count
     - person_count = @data_collector.total_push_author_count